2 package Class::MOP::Immutable;
7 use Class::MOP::Method::Constructor;
10 use Scalar::Util 'blessed';
12 our $VERSION = '0.03';
13 our $AUTHORITY = 'cpan:STEVAN';
16 my ($class, $metaclass, $options) = @_;
19 '$!metaclass' => $metaclass,
20 '%!options' => $options,
21 '$!immutable_metaclass' => undef,
25 # we initialize the immutable
26 # version of the metaclass here
27 $self->create_immutable_metaclass;
32 sub immutable_metaclass { (shift)->{'$!immutable_metaclass'} }
33 sub metaclass { (shift)->{'$!metaclass'} }
34 sub options { (shift)->{'%!options'} }
36 sub create_immutable_metaclass {
40 # The immutable version of the
41 # metaclass is just a anon-class
42 # which shadows the methods
44 $self->{'$!immutable_metaclass'} = Class::MOP::Class->create_anon_class(
45 superclasses => [ blessed($self->metaclass) ],
46 methods => $self->create_methods_for_immutable_metaclass,
51 my %DEFAULT_METHODS = (
52 # I don't really understand this, but removing it breaks tests (groditi)
55 # if it is not blessed, then someone is asking
56 # for the meta of Class::MOP::Class::Immutable
57 return Class::MOP::Class->initialize($self) unless blessed($self);
58 # otherwise, they are asking for the metaclass
59 # which has been made immutable, which is itself
62 is_mutable => sub { 0 },
63 is_immutable => sub { 1 },
64 make_immutable => sub { () },
68 # this will actually convert the
69 # existing metaclass to an immutable
71 sub make_metaclass_immutable {
72 my ($self, $metaclass, $options) = @_;
75 [ inline_accessors => 1 ],
76 [ inline_constructor => 1 ],
77 [ inline_destructor => 0 ],
78 [ constructor_name => 'new' ],
81 $options->{$pair->[0]} = $pair->[1] unless exists $options->{$pair->[0]};
84 my %options = %$options;
86 if ($options{inline_accessors}) {
87 foreach my $attr_name ($metaclass->get_attribute_list) {
88 # inline the accessors
89 $metaclass->get_attribute($attr_name)
90 ->install_accessors(1);
94 if ($options{inline_constructor}) {
95 my $constructor_class = $options{constructor_class} || 'Class::MOP::Method::Constructor';
96 $metaclass->add_method(
97 $options{constructor_name},
98 $constructor_class->new(
100 metaclass => $metaclass,
103 ) unless $metaclass->has_method($options{constructor_name});
106 if ($options{inline_destructor}) {
107 (exists $options{destructor_class})
108 || confess "The 'inline_destructor' option is present, but "
109 . "no destructor class was specified";
111 my $destructor_class = $options{destructor_class};
113 my $destructor = $destructor_class->new(
114 options => \%options,
115 metaclass => $metaclass,
118 $metaclass->add_method('DESTROY' => $destructor)
120 # we allow the destructor to determine
121 # if it is needed or not, it can perform
122 # all sorts of checks because it has the
124 if $destructor->is_needed;
127 my $memoized_methods = $self->options->{memoize};
128 foreach my $method_name (keys %{$memoized_methods}) {
129 my $type = $memoized_methods->{$method_name};
131 ($metaclass->can($method_name))
132 || confess "Could not find the method '$method_name' in " . $metaclass->name;
134 if ($type eq 'ARRAY') {
135 $metaclass->{'___' . $method_name} = [ $metaclass->$method_name ];
137 elsif ($type eq 'HASH') {
138 $metaclass->{'___' . $method_name} = { $metaclass->$method_name };
140 elsif ($type eq 'SCALAR') {
141 $metaclass->{'___' . $method_name} = $metaclass->$method_name;
145 $metaclass->{'___original_class'} = blessed($metaclass);
146 bless $metaclass => $self->immutable_metaclass->name;
149 sub make_metaclass_mutable {
150 my ($self, $immutable, $options) = @_;
152 my %options = %$options;
154 my $original_class = $immutable->get_mutable_metaclass_name;
155 delete $immutable->{'___original_class'} ;
156 bless $immutable => $original_class;
158 my $memoized_methods = $self->options->{memoize};
159 foreach my $method_name (keys %{$memoized_methods}) {
160 my $type = $memoized_methods->{$method_name};
162 ($immutable->can($method_name))
163 || confess "Could not find the method '$method_name' in " . $immutable->name;
164 if ($type eq 'SCALAR' || $type eq 'ARRAY' || $type eq 'HASH' ) {
165 delete $immutable->{'___' . $method_name};
169 if ($options{inline_destructor} && $immutable->has_method('DESTROY')) {
170 $immutable->remove_method('DESTROY')
171 if $immutable->get_method('DESTROY')->blessed eq $options{destructor_class};
175 # 14:01 <@stevan> nah,. you shouldnt
176 # 14:01 <@stevan> they are just inlined
177 # 14:01 <@stevan> which is the default in Moose anyway
178 # 14:02 <@stevan> and adding new attributes will just DWIM
179 # 14:02 <@stevan> and you really cant change an attribute anyway
180 # if ($options{inline_accessors}) {
181 # foreach my $attr_name ($immutable->get_attribute_list) {
182 # my $attr = $immutable->get_attribute($attr_name);
183 # $attr->remove_accessors;
184 # $attr->install_accessors(0);
188 # 14:26 <@stevan> the only user of ::Method::Constructor is immutable
189 # 14:27 <@stevan> if someone uses it outside of immutable,.. they are either: mst or groditi
190 # 14:27 <@stevan> so I am not worried
191 if ($options{inline_constructor}) {
192 my $constructor_class = $options{constructor_class} || 'Class::MOP::Method::Constructor';
193 $immutable->remove_method( $options{constructor_name} )
194 if $immutable->get_method($options{constructor_name})->blessed eq $constructor_class;
198 sub create_methods_for_immutable_metaclass {
201 my %methods = %DEFAULT_METHODS;
203 foreach my $read_only_method (@{$self->options->{read_only}}) {
204 my $method = $self->metaclass->meta->find_method_by_name($read_only_method);
207 || confess "Could not find the method '$read_only_method' in " . $self->metaclass->name;
209 $methods{$read_only_method} = sub {
210 confess "This method is read-only" if scalar @_ > 1;
211 goto &{$method->body}
215 foreach my $cannot_call_method (@{$self->options->{cannot_call}}) {
216 $methods{$cannot_call_method} = sub {
217 confess "This method ($cannot_call_method) cannot be called on an immutable instance";
221 my $memoized_methods = $self->options->{memoize};
222 foreach my $method_name (keys %{$memoized_methods}) {
223 my $type = $memoized_methods->{$method_name};
224 if ($type eq 'ARRAY') {
225 $methods{$method_name} = sub { @{$_[0]->{'___' . $method_name}} };
227 elsif ($type eq 'HASH') {
228 $methods{$method_name} = sub { %{$_[0]->{'___' . $method_name}} };
230 elsif ($type eq 'SCALAR') {
231 $methods{$method_name} = sub { $_[0]->{'___' . $method_name} };
235 $methods{get_mutable_metaclass_name} = sub { (shift)->{'___original_class'} };
248 Class::MOP::Immutable - A class to transform Class::MOP::Class metaclasses
252 use Class::MOP::Immutable;
254 my $immutable_metaclass = Class::MOP::Immutable->new($metaclass, {
255 read_only => [qw/superclasses/],
263 remove_package_symbol
266 class_precedence_list => 'ARRAY',
267 compute_all_applicable_attributes => 'ARRAY',
268 get_meta_instance => 'SCALAR',
269 get_method_map => 'SCALAR',
273 $immutable_metaclass->make_metaclass_immutable(@_)
277 This is basically a module for applying a transformation on a given
278 metaclass. Current features include making methods read-only,
279 making methods un-callable and memoizing methods (in a type specific
282 This module is fairly new to the MOP, and quite possibly will be
283 expanded and further generalized as the need arises.
289 =item B<new ($metaclass, \%options)>
291 Given a C<$metaclass> and a set of C<%options> this module will
292 prepare an immutable version of the C<$metaclass>, which can then
293 be applied to the C<$metaclass> using the C<make_metaclass_immutable>
298 Returns the options HASH set in C<new>.
302 Returns the metaclass set in C<new>.
304 =item B<immutable_metaclass>
306 Returns the immutable metaclass created within C<new>.
312 =item B<create_immutable_metaclass>
314 This will create the immutable version of the C<$metaclass>, but will
315 not actually change the original metaclass.
317 =item B<create_methods_for_immutable_metaclass>
319 This will create all the methods for the immutable metaclass based
320 on the C<%options> passed into C<new>.
322 =item B<make_metaclass_immutable (%options)>
324 This will actually change the C<$metaclass> into the immutable version.
326 =item B<make_metaclass_mutable (%options)>
328 This will change the C<$metaclass> into the mutable version by reversing
329 the immutable process. C<%options> should be the same options that were
330 given to make_metaclass_immutable.
336 Stevan Little E<lt>stevan@iinteractive.comE<gt>
338 =head1 COPYRIGHT AND LICENSE
340 Copyright 2006, 2007 by Infinity Interactive, Inc.
342 L<http://www.iinteractive.com>
344 This library is free software; you can redistribute it and/or modify
345 it under the same terms as Perl itself.